Change SSH Port and OS User

Scenario:

You installed as os user= 'root' and using ssh port 22. Now you want to change this to:

SSH port = 2222

OS user = johan

Requirements

• The OS user must be able to ssh without passwords to the other nodes.
• The OS user must be allowed to do sudo (be a sudoers)

Change ssh port

On each server, including the cluster control server do:

EDIT /etc/ssh/sshd_config

locate and change

# Port 22

to

Port 2222

Save and exit and do:

service sshd restart

Note:

You cannot disable root login (PermitRootLogin=no in SSH configuration) if the osuser/ssh_user/os_user defined in /etc/cmon.cnf is root. This will break the communication between ClusterControl node and the DB cluster.

Changes on the CMON controller 

On the controller do, replace <password> with the actual password for the osuser.

mysql -ucmon -p -h127.0.0.1 
use cmon
UPDATE cmon.cmon_configuration SET value='echo <password> | sudo -S' WHERE cid=1 AND param='SUDO';
# don't forget to update the staging dir (can also be done from the web interface)
# to a a directory writeable by the new 'osuser' (replace osuser with your actual setting)
UPDATE cmon.cmon_configuration SET value='/home/osuser/s9s_tmp/' WHERE cid=1 AND param='STAGING_DIR';

EDIT /etc/cmon.cnf (on the controller only). Make sure the following is set, and that it is only set once in the /etc/cmon.cnf. Update existing values instead of adding new ones:

osuser=johan 
ssh_opts=-nqtt
ssh_port=2222

Verify SSH Connections

Test your new SSH user's ssh connections from the Controller host.

# from the controller node 
ssh <new user>@127.0.0.1 # <- must also work because how we handle some CMON jobs 
ssh <new user>@<db nodes> 
ssh <new user>@<db nodes> "sudo ls"

Restart CMON Process

Last restart the Controller/CMON process to make the changes effective.

service cmon restart